Fabrication of gas discharge display devices generally of the character disclosed herein have been accomplished in the past. That is, individual glass substrates and/or ceramic substrates are provided upon which the conductor runs are printed and then the dielectric masks are printed over the conductor runs and in the openings in the conductor runs for the cathode electrodes, the cathode materials which interface with the gas discharge medium are printed thereon and all of these being subsequently fired and cured. Such devices are subsequently assembled usually by the use of a gas filling tubulation but in some cases tubulationless devices have been fabricated in which final hermetic seal of two spaced apart substrates is accomplished by utilization of an unfused sealing frame, evacuating the entire unit and back filling with an elevated temperature and then heating the assembled parts spaced between the electrode elements while retaining the gas in the assembly until the glass parts have been softened to a sealing temperature to result in a fusion sealing of the frame element and thereby final assembly of the device. This process is difficult and cumbersome and does not lend itself well to batch processing of individual display elements.
In Boswau U.S. Pat. No. 2,142,106, a gaseous discharge display device having small glass discs carrying shaped cathode elements and individual anode elements are stacked in a disc with the interstices between the discs sealed in a manner around the periphery to prevent electrode interference between each other, a small aperture being left at one point in the periphery by leaving out the sealing operation at this point to provide communication with the main gas chamber formed by an overall glass envelope or bulb. In the Boswau patent, the bulb is subsequently exhausted and filled with the gas at a proper pressure, the exhausting and back filling processes extending through and communicating through the aperture to the individual gas chambers formed in the spaced disc and the aperture then is filled with a suitable sealing material which permits the gas to permeate during the exhausting and filling operation thereafter this individual seal element or plug is sealed by heating means of electronic bombardment or other sealing means. The present invention is a direct and distinct improvement over the sealing technique disclosed in the Boswau patent in that the present invention adapts a portion of that technique of the Boswau patent to incorporate spacer elements in the sealant and extends same to batch processing of thousands of individual discrete gaseous discharge panel elements in a manner and fashion not heretofore available, with yield factors significantly greater than those of the prior art. A small opening or space between the ends of the rod is provided. Large numbers of the device may be stacked in trays and back filling with any desired gas composition of large numbers of individual devices in a single operation.
In accordance with this invention, instead of using a ceramic substrate, simple, inexpensive glass substrates are used. The conductor elements forming the cathode electrodes which interface with the gas medium are printed first and cured. At this time, the portions of the conductive printing which are actual anode elements, may be nickel plated with electrodeless nickel to reduce sputtering. During the nickel plating, the conductor portion to the exterior of the device are shielded. The reason for shielding is that the seal area must be sintered and not porous.
In the sealing operation described earlier herein, it has also been found that the use of screened on sealing materials in an unfused state permits the incorporation of the spacer therein and the forming of the seal under non-vacuum conditions permits such seals to be made, particularly when the glass gob sealing technique is utilized.
Then, after the gas filling has been introduced to the devices, the devices are heated by Calarod heaters inside the chamber so as to effect a melting of small glass sealing gobs in the fill ports or openings described earlier herein.